This invention relates generally to postage meters and is concerned more particularly, but not exclusively, with rotary print drum-type postal meters including the printing mechanisms and the value setting mechanisms thereof.
Postage meters are devices for dispensing value in the form of postage printed on a mailpiece such as an envelope. The term postage meter also includes other similar meters such as parcel post meters. Meters of this type print and account for postage stored in the meter. Mechanisms are provided in the meter to set a particular value of postage to be printed on a mailpiece.
Postage meters in use today typically include a set of four adjacent print wheels, each of which carries print element characters zero through nine. The print wheels can be independently positioned to allow a user to set any amount of postage between $00.00 (for test purposes) and $99.99.
The print wheels of postage meters have in the past generally been manually set by a user through a series of mechanical linkages and levers. Setting the print wheels manually is no problem for users who process relatively little mail on a daily basis. However, for higher volume users, the meter mechanisms have been adapted for automated operation in recent times.
Postage meters have also been developed with electronic accounting systems which has led to the development of printing mechanisms and value setting mechanisms which cooperate with the electronic circuits in a manner to enhance the capabilities of the postage meter.
U.S. Pat. No. 3,978,457 to Check et al, filed Dec. 23, 1974, describes an electronic postage meter in which the printing and value setting mechanism are electronically controlled. Each print wheel is set to position a different postage amount by an independently rotatable gear mechanism. The gear mechanisms are engaged by a master gear one at a time, a master gear being rotatably mounted within a laterally movable carriage. The carriage can be moved to cause the master gear to engage in turn with the gear mechanisms. The carriage is positioned by a pair of solenoids acting through a variable linkage and the master gear is driven by a stepper motor. The print drum is driven by a separate motor. An electronic control system is fully described for operating the value setting and printing mechanisms in correct sequence in accordance with values selected by inputting a keyboard. It will also be noted that the meter may be detachably mounted on a base containing certain mechanical drives although the drives for the setting mechanism are contained in the meter itself.
U.S. Pat. No. 4,050,374 to Check, filed June 21, 1976 describes a setting mechanism for a postage meter similar to that employed in the meter of earlier U.S. Pat. No. 3,978,457 aforesaid in which the solenoids for positioning the master gear carriage are replaced by a stepper motor. It also describes a mechanism for locking the print drum against rotation during value setting. Further aspects and alternatives to the setting mechanism of such postal meter systems are disclosed in U.S. Pat. Nos. 3,965,815 and 3,977,320 to Lupkis et al.
U.S. Pat. No. 4,287,825 to Eckert, Jr. et al, filed Oct. 30, 1979 discloses a setting mechanism like that in U.S. Pat. No. 4,050,374 referred to above with a modified locking mechanism for the print drum during value selection.
U.S. Pat. No. 4,367,676 to Clark, filed May 22, 1981, describes a different approach to value setting. Here a bank of value setting gears equal to the number of print wheels are drivingly connected to respective print wheels one at a time to set the print wheels. A pinion rotated by a stepper motor is shifted from setting gear to setting gear by a tracking mechanism driven by a separate motor which also rotates the print drum at the same time. U.S. Pat. No. 4,140,055 to Lellemand filed June 6, 1977 discloses a print wheel value changing system using a planet wheel transmission device in which an eccentrically mounted pinion meshes with a ring gear within a postage printing drum which supports the postage printing wheel.
U.S. Pat. Nos. 4,301,507 and 4,287,825 are also of interest; the former patent describing in detail an electronic control system for use in an electronic postage meter and the latter patent describing the mechanical aspects of the meter. Pending U.S. application Ser. No. 447,815, entitled "Stand-Alone Electronic Mailing Machine" by D. Buam and A. Eckert, filed on Dec. 8, 1982, assigned to the same assignee as the instant application, discloses further details of electronic control systems, as well as the mechanical aspects, suitable for postage meters and specifically describes a flat bed-type of printer.
Also of interest in this area are U.S. Pat. Nos. 3,965,815 and 3,977,320 which relate to electro-mechanical setting mechanisms for rotary drum postal meters. Other patents of general interest include U.S. Pat. Nos. 3,876,870; 3,890,491; 3,892,355; 3,916,361 and 3,949,203 issued to Malavazos et al.
The present invention embodies various improvements to postage meters generally and particularly to the printing mechanisms therefor. A novel system is disclosed for the setting of the postage value amounts in postage meters and for driving and operating the meter. The system includes, inter alia, a novel approach to moving the racks which control the value selection for printing on the mailpiece by the postal meter, particularly a system of the type having axially displaceable setting racks.
Different aspects of the invention as set forth herein variously include several advantages over prior art devices. The number of racks or other setting devices and, thus, the number of print devices, is not limited by the setting mechanism. In previous systems, a relatively small number of racks, such as four setting racks, had been used to change the four digits of postage ($00.00).
Aspects of the present invention permit a larger number of setting devices. This enables additinal changeable information, such as date, logos, cities, etc., to be placed on the postal stamp which can be quickly and easily varied. In addition, relatively speedy value setting is possible and relative compactness of the value selection system can be achieved. There is also a large reduction in the number of parts in the system compared with prior art devices with consequent cost reduction achieved.